Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 281737 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 137 PM EDT TUE OCT 28 2014 .SYNOPSIS... A COLD FRONT CROSSES TONIGHT...FEW THUNDERSTORMS WEST OF THE OHIO RIVER COULD CONTAIN GUSTY WINDS AND SMALL HAIL. HIGH PRESSURE ON THURSDAY. STRONGER COLD FRONT CROSSES LATE FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... BASED OFF OF MODELS AND RADAR...SPEED UP TIMING OF COLD FRONT FOR THIS AFTERNOON. OTHERWISE NO OTHER CHANGES ARE EXPECTED. PREVIOUS DISCUSSION... MAIN FOCUS THROUGH TONIGHT WILL BE COLD FRONT CROSSING THE FORECAST AREA...BRINGING A FAIRLY QUICK SHOT OF GUSTY SHOWERS THIS EVENING. MODELS IN PRETTY GOOD AGREEMENT IN TRACKING FEATURE ACROSS...WITH BAND OF PRECIPITATION REACHING THE OH RIVER BY ABOUT 00Z...AND WORKING ACROSS WV...REACHING THE EASTERN MOUNTAINS OF WV BY 08Z. FIGURE THE BEST CHANCES FOR STRONGER THUNDERSTORMS WILL BE ACROSS SE OH WHERE THERE MAY BE ENOUGH RESIDUAL DAYTIME HEATING AVAILABLE TO ENHANCE CONVECTIVE GROWTH. SWIFT SSW FLOW INVOF AND AHEAD OF BOUNDARY COULD TRANSLATE TO SFC FOR THE POSSIBILITY OF ISOLD SEVERE WIND GUSTS...MAINLY OVER SE OH. OTHERWISE...WITH THE LOSS OF DAYTIME HEATING..SHOWER WITH SPORADIC LIGHTNING SHOULD BE THE MODE OF OPERATION AFTER THE SUN GOES DOWN. MADE MINOR ADJUSTMENTS TO FORECAST...PUSHING POPS HIGHER AND TIGHTENING POP GRADIENT FROM 23Z-08Z. STAYED WITH INHERITED TEMPS...WHICH WHERE ON THE COOL SIDE OF THE BC GRIDS. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... ALL MODELS AGREE ON COLD FRONT BEING E OF THE APPALACHIANS COME 12Z WED. ANAFRONT / UPSLOPE SHOWERS ARE LIKELY TO STILL BE IN THE MOUNTAINS AT THAT TIME...BUT EXIT QUICKLY THEREAFTER AS DRY AIR ADVECTS IN BEHIND THE FRONT. LOW LEVEL MOISTURE ATOP THE MIXING LAYER BREAKS UP SOMEWHAT ON WED BEFORE RETURNING FROM THE N WED NT BENEATH MID AND UPPER LEVEL TROUGHINESS. HIGH PRESSURE CROSSES THU. THE LOW LEVEL MOISTURE DISSIPATES...BUT ONGOING UPPER LEVEL TROUGHINESS INTRODUCES MID AND HIGH CLOUD AS QUICKLY AS THE LOWER CLOUD COULD DRY UP. E COAST TROUGH AMPLIFICATION TAKES PLACE FRI INTO FRI NT. SRN STREAM UPPER LEVEL S/W TROUGH CROSSES THU NT INTO FRI...AND THEN NRN STREAM S/W DIGS SEWD THROUGH THE AREA FRI AFTERNOON AND NT. LOW PRESSURE FORMING OFFSHORE FRI IN RESPONSE TO THE FIRST ONE HELPS TO ASSURE LITTLE OR NO INFLOW AHEAD OF SFC COLD FRONT AHEAD OF NRN STREAM SYSTEM...WHICH CROSSES FRI AFTERNOON INTO FRI EVENING...ALL HALLOWS EVE. THE BEST CHANCE FOR SHOWERS IS FRI AFTERNOON AND EVENING...AS THE COLD FRONT CROSSES...FOLLOWED BY THE DIGGING NRN S/W...THE AXIS OF WHICH CROSSES AROUND 06Z SAT. SHOWERS DIMINISH AND BECOME CONFINED TO THE FAVORED NW FLOW UPSLOPE AREA BY SAT MORNING AS PRECIPITATION TYPE SWITCHES TO SNOW IN THE COLDER AIR IN THE MOUNTAINS. THE PRECIPITATION CUTS OFF BEFORE THE COLUMN GETS COLD ENOUGH TO SUPPORT SNOW FOR MUCH OF THE LOWLANDS. THERE IS SOME HISTORY IN PREVIOUS MODEL RUNS FOR THIS PARTICULAR EVENT...PARTICULARLY IN THE CASE OF THE ECMWF...WHICH HAS SHOWN THE NRN S/W CLOSING OFF OVER OR EVEN SW OF THE AREA AND REMAINING CLOSED OFF AS IT DRIFTED OFF THE E COAST IN VARIOUS WAYS DEPENDING ON THE RUN...EVEN LOITERING OVER THE SERN STATES FOR A TIME ON SOME RUNS. THE LATEST ECMWF HAS ACTUALLY RETURNED TO CLOSING OFF AN UPPER LOW OVER THE AREA FRI NT...AND THEN KEEPING IT CLOSED OFF AS IT MOVES OFF AND THEN UP THE E COAST OVER THE WEEKEND...EVENTUALLY COMBINING WITH ANOTHER S/W TROUGH. EVEN THE GFS CLOSES OFF AN UPPER LOW OVER THE AREA BRIEFLY FRI NT. THESE CLOSED OFF SOLNS WOULD DELIVER COLDER AND AND FORCING FARTHER W WHILE MAKING THE UPSLOPE FLOW MORE CYCLONIC IN RESPONSE TO SFC CYCLONE GENERATION NEARER THE AREA. THIS IN TURN WOULD INTRODUCE SOME SNOW ACCUMULATION IN THE MOUNTAINS AND THE SEASONS FIRST SNOWFLAKES FOR THE LOWLANDS. TEMPERATURES CLOSE TO GUIDANCE AND PREVIOUS FCST. DID BLEND IN MOSGUIDE FOR TEMPERATURES FRI NT TO BETTER TIME THE COLD ADVECTION AND THE CHANGEOVER...WHICH TAKES PLACE OVERNIGHT RATHER THAN IN THE EVENING. && .LONG TERM /SATURDAY THROUGH MONDAY/... WENT WITH WPC WITH A FEW CHANGES. SYN OPTICALLY...HAVE HIGH PRESSURE EXITING TO THE EAST TO START THE PERIOD. COLD FRONT PASSES FRIDAY. SOME TIMING DISCREPANCY BETWEEN THE ECMWF AND GFS BUT NOTHING REAL SIGNIFICANT. DID GO WITH A BIT HIGHER POPS THAN WPC FOR THIS TIME FRAME. MUCH COOLER AIR ARRIVES BEHIND THE COLD FRONT...WITH 850MB TEMPS DROPPING DOWN TO -6C TO -8C. THIS WILL BRING A TRANSITION OF RAIN TO SNOW LATE FRIDAY OR FRIDAY NIGHT. AS UPPER LEVEL TROUGH AXIS PASSES FRIDAY NIGHT...PRECIP WILL BECOME MORE UPSLOPE TYPE IN NW FLOW...WITH RAIN AND SNOW SHOWERS LINGERING INTO SATURDAY FOR THE MOUNTAINOUS COUNTIES. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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COLD FRONT ALONG SDF/ILN/DLZ LINE WITH A LINE OF SHOWERS AHEAD OF IT ALONG A LEX/FGX LINE. GUSTY WESTERLY WINDS OUT AHEAD OF BOTH LINES 10-15KTS GUSTING 20-25KTS. FIRST LINE TO AFFECT HTS/PKB BTW 20-23Z WITH VFR/MVFR CIGS AND VSBYS. THIS LINE ALONG WITH COLD FRONT WILL CONTINUE TO MOVE EASTWARD AND AFFECT TAF SITES...MAINLY BETWEEN 22Z-06Z. WINDS WITH THE FRONT AND JUST BEHIND WILL SWITCH TO NW 10-15KTS AND GUST 20-35KTS BEFORE DYING DOWN BTW 06Z-12Z. VFR CIGS TOWARDS 12Z AND FRONT EXITS AREA BY 18Z WED. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z WEDNESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING OF COLD FRONT COULD VARY THIS AFTERNOON AND EVENING ALONG WITH RW/CIGS AND VSBYS. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 CRW CONSISTENCY H H H H H H H H M H H H HTS CONSISTENCY H H H H H M M M M H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H M PKB CONSISTENCY H H H H H M M M M H H H CKB CONSISTENCY H H H H H H H H M H H H AFTER 18Z WEDNESDAY... IFR CONDITIONS POSSIBLE 06Z TO 14Z WEDNESDAY IN STRATUS AND LINGERING RAIN IN THE MOUNTAINS OF WEST VIRGINIA INTO SOUTHWEST VIRGINIA. SOME IFR IN VALLEY FOG IN WEST VIRGINIA 06Z TO 12Z THURSDAY. IFR IN STRATUS POSSIBLE FRI NT INTO SAT...AND EVEN IN SNOW SHOWERS OVER THE HIGHER MOUNTAINOUS TERRAIN OVERNIGHT FRI NT.
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&& .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...KMC/TRM NEAR TERM...JS/KMC SHORT TERM...TRM LONG TERM...MZ AVIATION...JS

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